Re: [PATCH 1/3] drm/xe: Disable compression on SVM

[Matthew Brost <matthew.brost@intel.com>]

On Tue, Jul 15, 2025 at 01:56:42PM +0530, Ghimiray, Himal Prasad wrote:
> 
> 
> On 15-07-2025 13:45, Matthew Auld wrote:
> > On 14/07/2025 18:33, Matthew Brost wrote:
> > > This is not yet supported, forcefully disable by setting pat_index to
> > > zero for CPU address mirror VMAs.
> > > 
> > > Cc: stable@vger.kernel.org
> > > Fixes: b43e864af0d4 ("drm/xe/uapi: Add
> > > DRM_XE_VM_BIND_FLAG_CPU_ADDR_MIRROR")
> > > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> > > ---
> > >   drivers/gpu/drm/xe/xe_vm.c | 5 ++++-
> > >   1 file changed, 4 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> > > index 2035604121e6..73cb981c0956 100644
> > > --- a/drivers/gpu/drm/xe/xe_vm.c
> > > +++ b/drivers/gpu/drm/xe/xe_vm.c
> > > @@ -2362,7 +2362,10 @@ vm_bind_ioctl_ops_create(struct xe_vm *vm,
> > > struct xe_vma_ops *vops,
> > >               op->map.is_cpu_addr_mirror = flags &
> > >                   DRM_XE_VM_BIND_FLAG_CPU_ADDR_MIRROR;
> > >               op->map.dumpable = flags & DRM_XE_VM_BIND_FLAG_DUMPABLE;
> > > -            op->map.pat_index = pat_index;
> > > +            if (op->map.is_cpu_addr_mirror)
> > > +                op->map.pat_index = 0;
> > 
> > Is this meant as a safe default or is this just a dummy value? If this
> > actually gets programmed in the hw, maybe XE_CACHE_WB would be better
> > here? That way we know exactly what it does from driver POV for a given
> > platform. Index zero for example might have no host coherency (might
> > then need WC on host). In some world index zero could enable
> > compression.
> 
> +1
> 

Will fix.

Matt

> > 
> > > +            else
> > > +                op->map.pat_index = pat_index;
> > >               op->map.invalidate_on_bind =
> > >                   __xe_vm_needs_clear_scratch_pages(vm, flags);
> > >           } else if (__op->op == DRM_GPUVA_OP_PREFETCH) {
> > 
>